Owls can't make tree holes, but they still nest in them. Boreal, elf, barn, and screech owls nest in woodpecker holes or naturally occurring tree cavities.
Most tree squirrels use woodpecker nests and tree holes. They won't construct their own tree holes, but they'll enlarge ones they discover. Leaf, grass, and squirrel fur line squirrel dreys.
They're vicious, even toward fellow minks, but they nest together. Females mate with many males to improve their offspring's DNA. Mink guard their area and tree nests after breeding season.
Native US bats are important to the ecosystem. As pollinators, they devour insects. Some bats roost throughout the day in tree holes and bark and hunt at night.
Two chickadee species build tree nests. Black-capped and Carolina chickadees hollow out trees with their beaks. These birds find a small tree hole and enlarge it for nesting.
Red-breasted and brown-headed nuthatches dig tree holes. If they can't find adequate aspens, they'll use other trees. These birds will reuse nests, but they prefer to build a new one each year.
Three duck species nest in the US. Bafflehead, goldeneye, and Barrow's goldeneye nest on trees. Strange: ducks in tree cavities. Ducklings leave their nests before they can care for themselves, unlike other tree cavity nesters.
Raccoons nest wherever they feel safe and comfortable, including tree holes. Raccoons take advantage of tree openings that fit them. They maintain many nests in case one is destroyed.